The human heart is a hollow muscular organ, responsible for pumping a large volume of blood around the human body every day. The ability to pump the blood is facilitated by several heart valves which open and close appropriately to allow blood passage through the heart. Heart valve dysfunction through natural defects or through the increasing incidence of heart disease, often requires the dysfunctional valve to be treated, with the main treatment modalities being mechanical adjustment of the valve or replacing the valve altogether. Current medical techniques are aimed at moving away from the major open heart surgery procedure, which is very traumatic for the patient, to more minimally invasive catheter based procedures, which are less traumatic, although more complicated procedures.
Catheter based procedures require precise positioning of the catheter, used to deliver for example the replacement valve, in an optimal position in relation to the cardiac valve to be treated. This is especially important as misalignment has the potential to damage adjacent cardiac structures leading to severe coronary complications. Placement of the catheter adjacent to a heart valve is hampered by the fact that the heart continues to pump throughout the procedure, giving rise to significant levels of turbulence which the catheter has to overcome to maintain its position. Furthermore, clotting of the blood leading to emboli is a continuous threat, as potentially they can lead to serious complications such as stroke.
In the US application 2009/0030510A1, it is disclosed that a significant obstacle to replacement of an aortic valve is the accurate placement of the medical device to replace the aortic valve. The solution taught to this problem is a temporary aortic valve (TAV) device. This is a catheter which has at the distal end a plurality of balloons, which can be inflated to stabilize the position of the TAV by applying pressure directly to the aortic walls of the patient. Further valve modulating tools can be passed through the lumen of the TAV. Between the balloons, blood is allowed to pass, simulating aortic valve function. This device is devised for the ablation and replacement of the aortic valve, with the balloons of the TAV fully inflated throughout the procedure to facilitate lodgment against the arterial walls.
The balloons are inflated throughout the entire medical procedure. As the balloons hamper bloodflow by restricting the available cross section for blood flow of the aortic lumen, potentially leading to leading a number of undesired issues. For instance, deliverable blood volume during the procedure may be reduced having potential dire consequences for the patient. Blood pressure may increase upstream the restriction created by the inflated balloons. The balloons may dislocate the longer time they are inflated in the aortic lumen, e.g. due to the increased blood pressure upstream thereof.
WO 2006/029370 and US 2009/0287182 discloses expandable transluminal sheaths. The distal end of the sheath is maintained in the first, low cross-sectional configuration during advancement through the atrial septum into the left atrium. The distal end of the sheath is expanded using a radial dialator, a balloon, to dialate the hole in the tissue of the atrial septum. A problem is that the device is not sufficiently stabilized for secure positioning. The radial expansion is purely for allowing the hole to heal more completely as opposed to cutting a large hole from the start.
US2005/0085842 discloses an expandable guide sheath. The sheath is advanced into a blood vessel in a contracted condition, expanded to an enlarged condition to define a lumen. The expanded lumen is for delivering fluids or instruments. Also in this prior art, a problem is that the device is not sufficiently stabilized for secure positioning. A filter is disclosed in the form of a hoop. The frame of the hoop is placed in circumferential apposition with the vessel for collecting emboli transported in the vessel.
US2003/0171803 discloses a similar hoop shaped filter basket with frame of the hoop placed in circumferential contact with the vessel wall.
US 2006/074484 A1 discloses a method and system for endovascular, endocardiac or endoluminal approach to a patient's heart. It is disclosed an embolic protection device for placement in the coronary sinuses. Guidewires terminate at the coronary sinuses and exit the patient at the thoracotomy access site, and a new valve may be inserted in the antegrade direction along the guidewires.
WO 2011/132080 A2 discloses a valvuloplasty catheter being introduced through a guide catheter until a balloon element is positioned across the aortic valve. The distal end of the guide catheter incorporates a tubular embolic filter element which is constrained in a collapsed configuration by constraint provided by an over tube. It is also discloses another type of embolic deflector mesh being applied to the upper aortic wall adjacent the aortic branches.
US 2008/147160 A1 discloses an instrument for positioning a cardiac valve prosthesis in a vessel including a wire element to slidingly guide the valve prosthesis towards an implantation site and an expandable element coupled to the wire element. The expandable element is expandable in the vessel to position the wire element in association with the implantation site.
WO 2005/023358 A1 discloses an apparatus and method to provide distal protection while accessing blood vessels within a patient's vasculature. A flexible sheath and distal protection element, e.g., a balloon or filter, are carried by a catheter. The sheath may be located on a distal region or may extend along the entire length of the catheter.
US 2010/211095 A1 discloses an embolic deflector that deploys via brachial or radial approach into the aorta to cover the ostia of the brachiocephalic and left common carotid artery.
Hence, improved or alternative medical devices and procedures for stabilizing the introducer sheath during cardiac valve replacement would be advantageous, in particular allowing for increased cost-effectiveness, and/or patient safety.